| // Copyright 2022 The Go Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| package coverage |
| |
| // Building the runtime package with coverage instrumentation enabled |
| // is tricky. For all other packages, you can be guaranteed that |
| // the package init function is run before any functions are executed, |
| // but this invariant is not maintained for packages such as "runtime", |
| // "internal/cpu", etc. To handle this, hard-code the package ID for |
| // the set of packages whose functions may be running before the |
| // init function of the package is complete. |
| // |
| // Hardcoding is unfortunate because it means that the tool that does |
| // coverage instrumentation has to keep a list of runtime packages, |
| // meaning that if someone makes changes to the pkg "runtime" |
| // dependencies, unexpected behavior will result for coverage builds. |
| // The coverage runtime will detect and report the unexpected |
| // behavior; look for an error of this form: |
| // |
| // internal error in coverage meta-data tracking: |
| // list of hard-coded runtime package IDs needs revising. |
| // registered list: |
| // slot: 0 path='internal/cpu' hard-coded id: 1 |
| // slot: 1 path='internal/goarch' hard-coded id: 2 |
| // slot: 2 path='runtime/internal/atomic' hard-coded id: 3 |
| // slot: 3 path='internal/goos' |
| // slot: 4 path='runtime/internal/sys' hard-coded id: 5 |
| // slot: 5 path='internal/abi' hard-coded id: 4 |
| // slot: 6 path='runtime/internal/math' hard-coded id: 6 |
| // slot: 7 path='internal/bytealg' hard-coded id: 7 |
| // slot: 8 path='internal/goexperiment' |
| // slot: 9 path='runtime/internal/syscall' hard-coded id: 8 |
| // slot: 10 path='runtime' hard-coded id: 9 |
| // fatal error: runtime.addCovMeta |
| // |
| // For the error above, the hard-coded list is missing "internal/goos" |
| // and "internal/goexperiment" ; the developer in question will need |
| // to copy the list above into "rtPkgs" below. |
| // |
| // Note: this strategy assumes that the list of dependencies of |
| // package runtime is fixed, and doesn't vary depending on OS/arch. If |
| // this were to be the case, we would need a table of some sort below |
| // as opposed to a fixed list. |
| |
| var rtPkgs = [...]string{ |
| "internal/cpu", |
| "internal/goarch", |
| "runtime/internal/atomic", |
| "internal/goos", |
| "internal/chacha8rand", |
| "runtime/internal/sys", |
| "internal/abi", |
| "runtime/internal/math", |
| "internal/bytealg", |
| "internal/goexperiment", |
| "runtime/internal/syscall", |
| "runtime", |
| } |
| |
| // Scoping note: the constants and apis in this file are internal |
| // only, not expected to ever be exposed outside of the runtime (unlike |
| // other coverage file formats and APIs, which will likely be shared |
| // at some point). |
| |
| // NotHardCoded is a package pseudo-ID indicating that a given package |
| // is not part of the runtime and doesn't require a hard-coded ID. |
| const NotHardCoded = -1 |
| |
| // HardCodedPkgID returns the hard-coded ID for the specified package |
| // path, or -1 if we don't use a hard-coded ID. Hard-coded IDs start |
| // at -2 and decrease as we go down the list. |
| func HardCodedPkgID(pkgpath string) int { |
| for k, p := range rtPkgs { |
| if p == pkgpath { |
| return (0 - k) - 2 |
| } |
| } |
| return NotHardCoded |
| } |